Median Thyroid Research Articles

High incidence of normal thyroid gland volume in patients with Graves' disease.

Thyroid function and thyroid gland volume, ultrasonically determined, were investigated in ninety consecutive untreated patients with Graves' disease. Twenty-eight patients (31%) had no clinically detectable goitre. Median thyroid gland volume was 31 ml (range 12-99 ml). Twenty-one patients (23%) had a normal calculated thyroid volume. Thyroid volume did not correlate with any measure of thyroid function. The lack of a goitre in a large portion of patients with Graves' disease could be responsible for delayed diagnosis and subsequent treatment of these patients.

Mouse Ultimobranchial Body not Mixed with the Thyroid: Four Cases1

SummaryFour cases in which the ultimobranchial body (UB) failed to fuse with the median thyroid primordium were observed. In these cases calcitonin‐containing cells were only found in the discrete UB which was found at the dorso‐lateral edge of the cricoid cartilage and in two cases had a diverticulum directed toward the cricothyroid ligament.

The thyroid of the sarcopterygian fishes (dipnoi and crossopterygii) and the origin of the tetrapod thyroid

The thyroid glands of the extant sarcopterygian fishes show the features which are retained in the thyroid glands of the tetrapods. Whole body scans of 131I injected dipnoans demonstrate a single thyroid area with no heterotopic thyroid present. The thyroids of all extant sarcopterygian genera are compact and encapsulated in contrast to diffuse thyroid tissue occurring in teleosts generally. The basic condition, a single median thyroid, is present in Neoceratodus forsteri and Latimeria chalumnae, while Lepidosiren paradoxa and Protopterus annectens show bifurcate thyroid glands. Cytomorphometric analysis of the thyroidal elements also reveals closer similarities to the Amphibia than to the teleosts. In addition, the Dipnoan radioiodine metabolism approximates that of the tetrapods rather than that of the teleosts. Thus, the fundamental features of the tetrapod thyroid were established in the Sarcopterygii early in the course of vertebrate evolution. Further, as in most of the higher vertebrate classes, parafollicular cells are not present in the sarcopterygian thyroid.

Cytochemical demonstration of alkaline phosphatase activity in the ultimobranchial bodies and thyroid parenchyma of the rat

AbstractThe localization of alkaline phosphatase activity in the ultimobranchial bodies was studied at the fine structural level in Holtzman rat embryos from the 15th to the 19th day of gestation, and also in four‐week old rats of the same strain. In the embryos, no alkaline phosphatase activity was found before the 17th day of gestation. From that day on, plasma membranes of glycogen‐rich cells show the reaction product regardless of their location in the wall of the ultimobranchial bodies. However, when the same cells are seen on cell cords of the median thyroid, they are negative. In the four‐week old rats, plasma membranes of ultimobranchial cells are strongly reactive. C cells are negative both before and after birth. Small thyroid follicular lumina with positive apical cell membranes are also noted in four‐week old rats. These positive thyroid follicles are not more differentiated than those previously described in 19‐day old rat embryos. It is concluded that new thyroid follicles are formed after birth. These results are discussed in relation to the hypothesis that when ultimobranchial cells are transformed into follicular cells, they undergo the same alkaline phosphatase changes as those observed during the maturation of follicular cells derived from the median thyroid primordium. The cytochemical method used is also criticized.

Ultrastructural localization of alkaline phosphatase activity in the developing thyroid gland of the rat.

AbstractThe localization of alkaline phosphatase activity during morphogenesis of the thyroid gland was studied at the fine structural level in Holtzman rats from the fifteenth day of foetal life till the first day after birth. The present work deals with the formation of thyroid follicles in the median thyroid primordium only. Since the rat thyroid does not develop synchronously, the three stages described may overlap during a given day of development. In the precolloid stage that extends roughly from the fifteenth to the nineteenth day of development, alkaline phosphatase activity is localized in Golgi saccules and vesicles and also in smooth membrane tubules and vesicles found in the cytoplasm near the lateral plasma membranes. At the end of this stage the lateral plasma membranes become strongly reactive and a cluster of positive vesicles and tubules appears immediately under the junctional zone. The second phase, the early colloid stage (17–19 days), is characterized by the formation of the colloid cavity in center of the disc‐like junctional zone: at this moment the newly formed apical plasma membrane bearing the microvilli shows the reaction product. During the third stage (18 days onwards), which starts with a gradual increase in the diameter of follicular lumina, a drastic fall in alkaline phosphatase activity is observed. In one day old rats, follicular cells are completely negative. These findings are briefly discussed in connection with thyroid cell differentiation.

The early development of the median thyroid gland of the mouse. A light-, electron-microscopic and histochemical study.

The mesobranchial area and the median thyroid anlage of embryonic albino mice were investigated from the somite stage 4 to 40 (81/2–10 days of gestation). In stage I (5–25 somites), there is an unequal growth and differentiation of the epithelium in the floor of the pharynx, whereby a mesobranchial area with a stratified or pseudostratified epithelium is formed. This area is distinct from the remaining pharyngeal epithelium, among other things by an apical microfilament system in the superficial epithelial cells. It is found just basal to a row of plump cytoplasmic protrusions, which extend into the lumen of the pharynx. In stage II (26–40 somites), the cranial part (median thyroid anlage) of the mesobranchial area thickens in relation to the caudal part and grows down into the underlying mesenchyme. The filament system is concentrated in the superficial cell layer of the median thyroid anlage at the beginning of stage II and disappears during downgrowth.

Origin of cholinesterase-containing follicle cells and parafollicular cells of the developing thyroid gland in the rat.

The location of cholinesterase-containing cells in the thyroid gland and its precursors (median thyroid primordium and ultimobranchial bodies) has been investigated light-microscopically in rat embryos from the 13 to the 20th day of gestation.

Electron microscopic observations on the contribution of the ultimobranchial bodies to thyroid histogenesis in the rat.

AbstractThe fine structure of ultimobranchial bodies in the rat has been studied from the fifteenth to the twentieth day of gestation. At 15 days, the ultimobranchial bodies were still separated from the median thyroid primordium by connective tissue. Their lumina were filled with cellular debris and their thick walls were made up of one type of cell in which rough‐surfaced endoplasmic reticulum was scanty. Early in the sixteenth day, cell cords from the median thyroid primordium came in direct contact with the ultimobranchial bodies; no basal lamina separated them. At 17 days the walls of the ultimobranchial bodies were composed of C cells, glycogen‐rich cells and cells that were poor in rough‐surfaced membranes and glycogen. At 18 days three types of cells were present in cell cords in direct contact with the ultimobranchial bodies: C cells, glycogen‐rich cells and follicular cells. The first two cell types had migrated from the ultimobranchial bodies while the follicular cells had originated from the median primordium. In the same cell cords, follicular cells containing glycogen granules were interpreted as being an intermediate stage between glycogen‐rich cells and true follicular cells. In follicular cells of the isthmus region, which presumably originate from the median primordium alone, glycogen granules were not observed after the fifteenth day of development. It is concluded that C cells and few follicular cells are of ultimobranchial origin.

Surgical management of subhyoid median ectopic thyroid

Surgical management of subhyoid median ectopic thyroid